Self-feeding carburetor



' Aug. 23, 1927.

H. E. MARSH SELF FEEDING 'CARBURETOR Filed AugvlO. 1925 Patented Aug. 23, 1927.

UNITED STATES PATENT OFFICE.

HOWARD E; MARSH, OF LOMPOC, CALIFORNIA.

SELF-FEEDING CABBURBTOB.

Application and August 10, 1925. Serial no; 49,351.

needle valve operated by the float, thus avoiding troubles that arise from the use of a needle valve as, for example. in seating properly because of wear or fouling.

Another object is to provide a construction in which two chambers are required instead-of three as in the prior patented carburetor mentioned above.

Another object is to avoid a reduction of pressurebehind the fuel as it is drawn by the engine suction into the mixing chamber.

A'furt-her object is toprovide novel means for controlling the flow of fuel into the mixing chamber.

Other objects and advantages will appear in the subjoined detailed description.

T he accompanying drawings illustrate the invention 1 v v F 1 is a plan view of self feeding carburetor constructed in accordance with the provisions of this invention. I

Fig. 2 is a. sectional elevation on the line indicated by 2 -2, Fig. 1.

Fig. 3 is an enlarged fragmental section on the line indicated by 33, Fig. 1.

Fig. 4 is an enlarged fragmental plan section on the irregular line indicated by 44, Fi 2.

Twochambers are provided. a. chamber 5 and a. chamber 6. In this instance, the chamber 6 is positioned inside of the chamher 5 and concentric therewith, being provided at its upper end with an outwardly projecting flange-7 which rests upon the upper edge ofthe chamber 5 and is clamped between said upper edge and a cover'8. The cover 8 is secured in place byscrews or other fastenings 9 and is provided with a fuelinlet 64 adapted for connection by afucl pipe, not shown, with a source of fuel supply. The chamber 5 is the suppl chamber for fuel and is provided in its ottom with a drain cock 10 and near the top'with a port 65 that opens to the atmosphere. The chamher 6 is the float chamber containingafloat is formed in the cover. the lever-16 engages in a vertical slot 21 of 11 of suitable construction as, for example, of hollow metal construction. Secured to the bottom of the chamber 6 and projecting upwardly therein is guide member 12 which is accommodated in a vertical hole 13 in the float 11 so as toguide the float as itris'es and falls and prevent it from engaging the .s'ide walls of the. chamber 6 or assuming a level position when the carburetor is'tilted.

.The float is provided on its top with a slotted member 14, the slot 15 therein being verticaland being engaged by one of the arms of a bell crank lever 16 which is ful- "crumed at 17 on a bracket 18 that projects downwardly from the cover 8. Thus,when the cover is removed, the lever 16 comes with it. The other arm of the lever 16'proj'ects through an'opening 19 in the cover 8and into a valve chamber 2O that, in this instance This other arm of an ear 22 that projects from a-cylindrical valve 23 provided in its periphery with an annular groove orp'ort 24. The valve chamber has a removable head 25 that is screwed :into place.

The chamber 20 isprovided in its top with a suction port 2'6 that extends through a boss 27 provided with threads so that it may be connected by a union, not shown to the intake manifold of the engine with which the carburetor functions. The valve chamber 20-i's provided in its bottom with a pair of'ports' 2B, 29 whichcommunicate with the float chamber 6.- 'The port 28 is a suction port for exhausting air from the fioatcchamber '6 and is in alignment with the port'26 and, accordingly, the port 24 will register simultaneously with the ports 26, 28 when the'valve is moved sulficiently far to the right in Fig. 2 "by appropriate drop of the float 11. Whenthe float rises above the positionshown in Fig. 2 it moves the valve 23jto the'left so as to simultaneously register the port 24 with the port .29 and with a port at is vertically-aligned with the port 29 and that opens laterally from the valve chamber'QO'and'communicates with the atmosphere. v

The 'bottomof the chamber 6 is provided with a port or ports 31 communicating with the chamber 5, there being a check'fla'p valve lUU chamber 6 and to admit, when open, of flow of fuel from the chamber 6 through the ports 31 into the chamber 5. The valve 32 is pivoted at 33 to a lever 34 that, preferably, is weighted at 35 on its outer end so that said lever will function to yieldingly hold the valve 32 closed when the pressures in the chambers 5, 6 are equal. The lever 34 is fulcrumed at 36 to a bracket 37 projecting downwardly from the bottom of the charm ber 6. The valve 32 is guided by astem 38 that projects into a vertical guideway 39 formed in the lower end of the member 12.

The wall of the chamber 5 is sufliciently thick at one place to form a valve chamber 40, the inner face of the wall of the chamber 40 being formed by a circular sleeve 41 provided with a longitudinally extending slot 42 that preferably expands outwardly so that foreign substances that may be in the fuel will not stick fast in the slot. The

sleeve is held from turning by a pin 67.

Communicating with the slot 42 is a nozzle slot duct or orifice 43 that opens into the mixing chamber 44 of the carburetor. In serted in the sleeve 41 and slidable therein is a' cylindrical valve 45 provided in its periphery with a projection 46 that slides in the slot 42 so as to prevent turning of the valve 45 in the sleeve when a stem 47, that is screw threaded into the valve 45, is rotated. The stem 47 projects through a head 48 that closes one end of the valve chamber 40, the other end of said valve chamber be ing closed by a head 49. The projecting end of the stem 47 is provided with an arm 50 by which said stem is turned so as to cause the valve 45 to move endwise to cover more through a duct 51 that leads from said chamber to the lower portion of the chamber 5. In order that the fuel admitted to one end of the chamber 40 from the duct 51 can pass through the valve 45 to the other end of said chamber said valve is provided with a longitudinally extending duct or ducts 52.

The passage 53 to the mixing chamber44 is provided with a butterfly valve 54 and the passage 55 leading'from the mixing chamber 44 is provided with a butterfly valve 56.

The valve 54 is operated by an arm 57 and the valve 56 is operated by an arm 58. In this instance, I connect the arms 57, 58 by a link 59 that is pivoted at 60, 61 to said arms, respectively. Also, in this instance, the arm 50 is connected by a link 62 with the arm 57 and link 59, the pivot 59 also passing through the link 62 and a pivot 63 connecting the links 62 with the arm 50. The arms 50, 57, 58 and the links 59, 62 are so proportioned and arranged as to produce the desired relative degree of opening of the valves 45, 54, 56 to economize in the use of the fuel.

It being assumed that the fuel intake 64 is connected with a fuel tank placed at a lower float 11 is in its lowermost position, and the motor is started in the usual manner, the valve 23 will be in position to'register its port 24 with the ports 26, 28, thus creating a partial vacuum in the chamber 6. This, as is readily understood, causes the fuel to flow into the float chamber and the float to rise. As the float rises it moves the port 24 out of registration with the ports 26, 28, but the inward flow of fuel continues because of the continued partial vacuum in the float chamber. l/Vhen the float 11 reaches a predetermined level, the valve 23 has been actuated into a position to register the port 24 with the ports 29, 30, thus admitting atmospheric air to the float so as to break the vacuum, and, accordingly, stop the inward flow of fuel. This breaking of the vacuum will occur when the level of fuel in the chamber 5 is slightly below the outlet end of the nozzle duct when the engine is not in operation, thus preventing flooding of the carburetor'at such time. As the engine operates, the liquid level in the chamber 5 varies very little because as soon as fuel is drawn from the chamber 5, the valve 32 will open, permitting fuel to flow from the float chamber 6 into the chamber 5. As the fuel is drawn from the float chamber, the float 11 will lower, thus again placing the chamber 6 in communication with the intake manifold of the engine so that a partial vacuum will be created in the float chamber and thus cause the inflow of fuel to the float chamber as before.

l/Vhen higher speed of the engine is desired, the arm 50 will be turned to cause the movement of the valve 45 in a direction to open to a wider extent the nozzle duct 43.

From the foregoing it will be readily understood thatthe carburetor is of comparatively simple construction, employing but few parts and operating in an efficient manner so as to obtainthe proper mixture of fuel and air required by the engine under dider- 'ent load conditions.

The various valves described above may we constructed differently than described so long as they functionvproperly to produce the desired results but I prefer to employ the construction described for the valve that controls the flow of fuel into the mixing chamber because of its nicety of positive adjustment.

It Will be noted that, because of the presence of the check valve for preventing backflow of fuel into the chamber 6, partial vacuum produced in the float chamber cannot tend to lower the liquid level in the chamber 5 to lessen the pressure behind the fuel as it is drawn by the engine suction into the mixing chamber.

I claim:

A self feeding carburetor comprising a mixing chamber, a fuel supply chamber communicating with the mixing chamber,

and opening to the atmosphere, a float chamber having a port opening into the fuel supply chamber, said float chamber provided with a constantly open fuel inlet, a check valve to prevent flow of fuel from the fuel supply chamber through the port, a float in the float chamber, a valve chamber having a suction port andhaving an air admission port communicating with the atmosphere, the float chamber provided with ports alined with the suction and air admission ports respectively, a cylindrical valve having a single port, and means operated by falling of the float to move the valve into position to register its port With the suction port and operated by rising of the float to move the valve into position to register its port Wit-l1 the air admission port.

Signed at Los Angeles, California, this 5th day of August, 1925.

I HOWARD E. MARSH. 

